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*NASA URGED TO SEEK OUT INTELLIGENT LIFE*
Space scientists in America have a new dream - to discover another
planet like Earth, writes Robin McKie.
American scientists are planning to go fishing - for planets. A
growing research lobby believes the United States should channel it's
space resources towards detecting other solar systems that might
support life. The move would shift funding away from expensive manned
expeditions, for instance to Mars, and would instead exploit
recently established technologies for building oriting observatories,
such as the Hubble space telescope.
Robert Brown of the Space Telescope Science Institute in Baltimore
says: "Such a hunt would strike a chord with the public. The
National Aeronautics and Space Administration (NASA) is trying to
find a purpose for it's existance. It could do no better than this.
It would be popular and make a real contribution to history.
Dr Brown, speaking last week at the American Association for the
Advancement of Science, is a noted enthusiast for planet-hunting. But
he is not alone. Several other speakers stressed that they now
believe solar-system spotting has matured sufficiently to begin
realistic hunts. Nasa is currently seeking a new rationale. It's
orbiting space-station, Freedom, only just survived a series of
congressional budget cuts and the agency's traditional approach of
planning ever more ambitious manned missions, to culminate in a $50
billion (u31 billion) landing on Mars early next century looks
increasingly vulnerable. Critics argue that the two-year mission
would only prove what we already know - that Mars is red, dead, and
boring. The popular alternative within the space community would be
to commit NASA to a search for other worlds, a task which has
previously stumped astronomers because stars emit a billion times
more light than even the largest planets, like Jupiter. Observer's
ability to see smaller, warmer worlds (where life has it's best
prospects) against the glare of the stars has therefore proved to be
limited. Nevertheless, the first planets have been hooked. At
Pennsylvania State University, Dr. Aleksander Wolszczan has detected
three - in orbit around a star called PSR 1257+12. The star is a
pulsar, an old, extremely dense object, 12 miles in diameter, which
revolves at an astonishing 160 times per second. From
perturberations in the regular pulses emmitted by this "astronomical
lighthouse", Dr. Wolszczan detected two planets slightly bigger han
Earth and one much smaller, about the size of Mercury. His discovery
suggests planets may be ubiquitous, for if they can survive near
pulsars, created when starts first explode as supernovae and then
condense in on themselves, they should exist everywhere. The
cataclysmic creation of PSR 1257+12 should have destroyed any planets
in it's vicinity. So how did they get there? Researchers speculate
that PSR 1257+12 may have had a companion star from which the pulsar
slowly drew off gas and dust until it's partner was destroyed. From
the debris planets evolved. Life there must be slightly odd, however.
"You would have to protect yourself against a giant pulsing x-ray
machine," Dr. Wolszczan said. "You would have to carry a lead
umbrella all the time." Not surprisingly, scientists look to other,
far more "normal" stars for signs of planets that might support life.
"There are about 1,000 stars like our Sun within 100 light years of
Earth, so there should be no shortage of fish in our pond," said
David Latham of the Harvard-Smithsonian Centre for astrophysics. "For
example, Tau Ceti, near the constellation Pisces, is only 11.7 light
years distant and is extraordinarily like our Sun. It must be a very
good prospect." And if there are plenty of promising stars, ans
evidence that planets are ubiquitous, our extra-terrestial search
should have considerable promise. Unfortunatly, other conference
speakers provided evidence that undermined this optimism. Research
by Andrea Ghez of the university of California, Los Angeles, has
found that three-quarters of young stars are born with one or more
companion stars. "That is bad news for planets' prospects," she
said. "Planets form out of disks of dusk that slowly accrete into
larger and larger bodies. A companion star would sweep through these
disks, depleting the dust and rocks. There would not be enough left
for planets. Solar systems may be the the exception, not the rule,
in our galaxy."
Scientists are faced, therefore, with contradictory evidence about
the ubiquity of other worlds. But now they posses the means to
begin to find out who is right. "We have finally built a telescope
outside our atmosphere which will detect other planets," Dr. Brown
said. "We will soon finish the Copernican Revolution. We have shown
planets go around the Sun, but may soon be able to show they go round
other stars as well." Dr. Brown said advanced cameras were due to be
flown to the space telescope in 2002. These would exploit methods,
known as Fourier techniques, which would suppress the glare of o star
and reveal it's planets, if any. Once these new worlds had been
detected, a new space telescope, on the Moon or in deep space -
could be built to study such planets' atmospheres for the presence of
chemicals produced by living beings. Such a telecscope would
probably exploit the principles of interferometry, in which two
seperate instruments combine to produce extremely powerful
observations.
If it sounds like a dream, consider the words of the
NASA director Daniel Goldin: "What if we were to build an
interferometer on the moon? And what if it were big enough that we
could not only image planets around distant stars, but do
spectroscopic analyses of their atmospheres? Results might "change
our society in matters we can't even comprehend". Humanity would
either learn that life is rare, and therefore precious, or that
humans are just an "ever so 'umble" species in an alien-filled
universe. "We should get the answer soon," Dr. Brown said. "We have
put out hooks. Soon we will be draining the lake.."
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"change our society in matters we can't even comprehend"
Hmmm.. sounds as if "they" are preparing to "find" some aliens.. :)
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